Density dependence in the thermal conductivity of cellulose fiber mats and wood shavings mats: investigation of the apparent thermal conductivity of coarse pores

• DOI: 10.1007/s10086-015-1523-6
• Publication Date: 2015-11-03T08:14:10Z
• Authors: Noboru Sekino
• Keywords: 0401 agriculture, forestry, and fisheries; 04 agricultural and veterinary sciences; 01 natural sciences; 0104 chemical sciences

Thermal conductivities (k-values) of cellulose fiber (CF) and wood shavings (WS) mats were measured, and the density dependence of k-values in the ranges 28–60 and 60–100 kg/m3 for CF mats and WS mats, respectively, was investigated. The k-value of the CF mats tended to increase with increasing mat density, but that of the WS mats showed a much weaker relationship. In order to discuss this density dependence in k-values, the apparent thermal conductivity (k cp) of coarse pores in the mats, which includes the effects of convective and radiant heat transfer, was calculated. The results revealed that the density dependence in the k-values of the CF mats derived only from an increase in the number of heat bridges, consisting of fibers and their contact points. Also, the smaller density dependence of the k-values of the WS mats than that of the CF mats was found to be explicable by the density dependence of k cp in the WS mats, because a lower k cp at higher mat densities contributes to the lowering of mat thermal conductivity in a way that balances the increase in heat bridges as mat density increases.